Combining magnetic resonance (MR) examinations and positron emission tomography (PET) into one scanner with an identical imaging area is disclosed for example in U.S. Pat. No. 4,939,464. In this prior art, optical signals from a scintillation crystal are passed out of the measuring space to photodetectors via optical waveguides. The photodetectors are arranged outside the measuring space because they have to be protected from interactions with the magnetic fields required for the MR examinations.
Furthermore, DE 10 2005 015 070 discloses a combined positron emission tomography and magnetic resonance imaging scanner having a positron emission tomography scanner and a magnetic resonance imaging scanner. In the case of this prior art having the object of a very compact design, the positron emission tomography scanner part is arranged between a radio-frequency shield and a radio-frequency antenna device and is provided with shield cladding against radio-frequency radiation on the side of the radio-frequency antenna device.
When combining MR examinations with positron emission tomography, the structure with the PET scintillation crystals (PET gantry) must be arranged within the gradient coil of the MR system. Because the space available is extremely limited, the installation gap between the gradient coil and the PET construction is only a few millimeters wide.
This results in the problem that vibration of the surface of the gradient coil (a few 10 grams) is transferred to the PET gantry with almost no damping. This in turn leads to considerable loads on the PET gantry comprising the PET detectors, adhesively bonded crystal blocks and, possibly, sensitive electronics and plug connections which can be subjected to only a limited amount of mechanical stress.
DE 102 45 942 A1 discloses a magnetic resonance imaging scanner in which an internal pressure in a flexible hollow body between a boundary face of a cavity and a surface of a gradient coil system can be adjusted such that the gap can be sealed externally.
U.S. Pat. No. 4,639,672 discloses a nuclear magnetic resonance apparatus in which a sleeve is arranged within the gradient coils of the magnetic system, and forms a noise-absorbing shield between the gradient coils and the measurement space. Preferably, this is an evacuated space and a support for the gradient coils.